A typical flyback converter includes a primary side circuit, a transformer, and a secondary side circuit. The primary side circuit is connected to a power source and includes at least one switching element that controls the amount of energy transferred to the secondary side through the transformer. The transformer serves as an electrically isolated channel to transfer energy from the primary side circuit to the secondary side circuit. The secondary side circuit powers a load using the received energy.
In general, a classic flyback converter (using a secondary side rectification diode) is a unidirectional device. For example, energy is conveyed through the transformer from a primary winding to a secondary winding to produce an output voltage that powers a load. In the event that the load instantaneously consumes less power, the magnitude of the output voltage may spike or overshoot. This is an undesirable because the over-voltage condition, even if temporary, may cause damage to a respective load (circuit) being powered.